One of the weak sides of the 1Dx is noise in deep shadows at base ISO.It seems that nobody is arguing about that any more. DXO 1Dx measurement results also show that very clearly on their measurement curves.And I believe that nobody would be arguing that performance in this area is very critical for not just few people but for many people - for landscape photography, evening/night city shots and other sort of photography. Though it is easy to argue that that Nikon D800 would be the better choice BUT why not to see how we could get better deep shadow SNR from 1Dx.In one of my posts I mentioned that 1Dx has a very nice feature that could be used for that.I will not name it now (will do at SOME next post) but here is some magic - example how it works (snapshots from LR screen - noise reduction is totally disabled )1. First image shows 1dX shot at IS100 with EV=(-3) the Data Color noise calibration chart which was used for Noise Ninja NR S/W and PS plug-in. Shot with manual Out of Focus to blur target texture so it would not interfere with noise2. Second one is the same with Exposure slider in LR set to +3 - looks the same as normal shot with EV=03. Third image is 200% crop of shot with EV=0 showing normal 1Dx ISO shadow noise4. Fourth one is 200% crop of the EV=-3 shot with LR exposure set to +3 to raise shadows to normal level. Level of 1Dx noise at ISO100 at -3 EV shadows is very clearly seen

And next post is little bit of magic - the similar EV=(-3) shoot from 1Dx recovered in LR - 200% crop to see the difference in SNR for random nose with the previous shot.

canon rumors FORUM

OK, now is 200% crop of the similar EV=(-3) shoot from 1Dx using some special shooting method with 1Dx . Shadows are recovered in LR with Exposure slider set to +3 to compensate for in camera EV =(-3) . No noise reduction in LR.Note how SNR for random noise was improved.

So we have almost two stops improvement here for random noise SNR.This means that with normal exposure it is possible to successfully recover details in very deep shadows at ISO100. We still see some slight pattern noise on the image but I believe that there is some NR software that doing very well with reducing pattern noise - might be Topaz De-noise but not very sure as I do not have that. If all combined together with some special shooting method with 1Dx it is possible to get shadow SNR on par with Nikon D800.So now quiz - how this was done?

But seriously this method used for decades for filtering noise out in different applications.This is use of simple math in real life use.Noise is random - image is fixed.So what is required is just to integrate information element for a longer time and random noise would be filtered out. I believe that this is something that also was being used in astronomy to separate low level image details that could be even below random noise level. Also used in communication systems.========= So how this is done with 1Dx ------1Dx has one feature which is intended for some artistic work but it could be used for something completely different. This feature is multi-exposure – in one of the posts I mentioned about this for filtering out noise.You can take up to 9 shots and 1Dx will average these shots into one. As each shot has it's own random noise distribution then averaging 9 shots into one would essentially suppress noise - only fixed elements will be kept - so random electronic noise is significantly reduced but fixed patterns - real image or sensor defects are kept and cleared out of noise. This is equivalent to 9 times of longer integration time of the information element in the image detector.

How to do this in 1Dx:Enable multi-exposure continuous shooting, number of exposures to 9, multi-exposure control to Average (to integrate over 9 images) , put mirror lock up with the set button release to reduce camera vibration (will be returned back by set button) , put camera in high speed continuous shooting mode, press shutter - mirror will be locked, press shutter again and keep it pressed - camera will take quickly 9 images in less than 1 sec , stops and then merge it ( integrate) into one image.And you are done.Now press set button to return mirror back and then you could see the result.So nothing special - just to see things a bit deeper)))Method is suitable for only still images .In normal conditions such kind of shot will take about 0.75 sec with FPS =12And of course could be only shot using strong stable tripod for camera.

Thought that might be the 'trick'. I use it all the time in photomicroscopy. Works great for test charts and fixed tissue. Not so well with anything that moves, which limits its utility for >95% of what I shoot...

This is routinely applied in astrophotograpy if combined with precision German Equatorial Mounts. It is also used when combining many video frames into one photo (see registax). But I doubt it can be used elsewhere. You have to exclude leaves, people, water, clouds maybe and I am sure I haven't thought of everything...